Richard walter



Patented May 20, 1924.

UNITED STATES RICHARD WALTER, OF DUSSELDORF, GERMANY.

METHOD OF MAKING ALLOYS.

No Drawing.

To all whom it may concern:

Be it known that I, RICHARD WVALTER, residing at Dusseldorf, Germany, a citizen of the German Empire, have invented certain new and useful Improvements in Methods of Making Alloys (for which I filed applications in Austria Mar. 20, 1918, and in Ger many May 28, 1919), of which the following is a specification.

This invention relates to improvements in making alloys and more particularly to a process for alloying metals of the iron and chromium groups with silicon and its compounds.

The principal object of the invention is to generally improve upon the process for mak ing acid-proof alloys to be used for casting chemical apparatus.

Another object is to adapt the process to the daily varying requirements of a foundry and to avoid the use of converters or open hearth furnaces and other equipments costly in installation and operation which have been hitherto used for such purpose, using instead the simple and handy reverberatory furnace.

Another object of the invention is to save fuel and labor and to produce in a short time a homogeneous alloy of proper temperature for casting, reducing the formation of slag to the least possible quantity.

Still another object is to produce by a simple process an alloy of predetermined composition which only contains a certain low percentage of carbon and is almost free from undesirable foreign constituents.

In the processes hitherto employed in the manufacture of acid proof apparatus it was difficult to obtain castings which come out faultless and do not crack when heated in use.

For the purpose of decreasing the very un desirable hardness of such alloys resulting from high percentage of silicon, iron poor in carbon, such as wrought iron, soft iron, or steel scraps were used for making up the bulk of the charge, which means melting down large quantities of metal having a very high melting point.

It is obvious that the cupola of the foundry is not the proper equipment for this purpose; besides taking a long time to melt such charge down, a uniform reliable composition and purity of the alloy cannot be obtained due to the influence of foreign matter with which the metal comes in con- Application filed June 28, 1920. Serial No. 392,501.

tact, while passing through the cupola. Also the crucible furnace does not come in question for practical manufacture of the large size castings used in the chemical industry. The electrical furnace, although being generally the ideal means for alloying iron is in most cases out of the question, due

to the'high cost of current. The open hearth furnace which of course is most appropriate requires continuous operation and, besides being very expensive, cannot be adapted to the daily varying requirements of a foundry. The converter with the machinery connected therewith is also very expensive and does not yield an alloy of reliable composi tion and quality, besides consuming considerable quantities of expensive material.

All these disadvantages are avoided by my new process which, in addition, yields an alloy of reliable and uniform predetermined composition and just of the right pouring temperature.

My invention makes it possible to use a simple reverberatory furnace which is the cheapest furnace and very handy in many foundries, and to produce in such a furnace the silicon alloy which has the predetermined composition, is thoroughly homogeneous and has the proper temperature for pouring, with the least possible consumption of fuel.

In using my new process for the making of the acid proof iron silicon alloy, the percentage of silicon in which varies according to requirements from live to twenty-five per cent I heat a calculated charge of wrought iron, soft steel or the like together with the necessary amount of silicon, preferably in form of commercial ferro-silicon of a predetermined high content of silicon.

The components, iron and silicon, in lump form are dumped into the furnace in roughly intermixed state. The furnace is then heated from without in any suitable manner to a temperature at which exothermic reaction is initiated in the charge, which will be at a temperature several 100 degrees C. below the fusing joint of the components at about 1250 or roughly between 1200 and 1300 C. It suflices if at the stated temperature a piece of iron or the like and a piece of silicon are in contact, at which point of contact the reaction will then start with an abrupt rise in the temperature curve and will then quickly, almost instantaneously, flash throughout the entire mass. In practical operation the entire charge of a large furnace, after the reaction temperature has been reached. and reaction has set in at a single spot, will spontaneously melt down within a few seconds. The reaction may also be started by prodding or striking the solid charge with an iron rod whereby local pressure between the more or less loosely contacting components is exerted. The resuit Olii this violent reaction is a complete liquefaction and the "formation of a thoroughly homogeneous alloy, which readily separates from slag and other impurities, of which there will be very little at best owing to the quickness and thoroughness of the conversion.

It will be understood that the process can be adapted, within the scope of the same invention, to the use of silicon in the form of various silicon compounds and of almost pure silicon, either alone, or in mixture.

lit will be further understood that the same invention may he used for alloying other metals of the iron group such as manganese, nickel and cobalt, and also of metals of the chromium group, (chromium, tungsten, etc.) with silicon, the latter being preferably introduced in form of one of its compounds such as ferro silicon, silicon-manganese, or the like, however, also pure or commercial silicon may be used alone or mixed with its compounds.

Since pure silicon is too expensive for use on a large scale for industrial purposes, it will be found to answer the purpose to use high per cent ferro-silicon (8090%). Viith such percentage the exothermic reaction will proceed as set forth, and it will even take place in the case of commercial 45% ferrosilicon, although in this latter instance it will not reach quite as high a temperature as in the case of the higher per cent material.

It is also to be understood that my method is not confined to the use of a reverberatory furnace and that other kinds of flame heated furnace chambers may be adapted to my invention, provided that they can hold a bulky charge, are equipped with means to raise the temperature to the reaction point and with a hearth for collecting and refinin the alloy.

W hat T claim is 1- 1. The process of alloying silicon with metals of high melting point, which consists in heating a mixture of said components to a temperature at which exothermic reaction is initiated, and in then using this reaction to melt down the charge and complete the process.

2. The process of making alloys of metals of the iron and chromium groups and silicon, wiich consists in heating the intermixed components to a temperature at which exothermic reaction sets in, and in then using this reaction to melt down the charge and complete the process.

3. The process of making alloys of metals of the iron and chromium groups and silicon compounds of m tale of said respective groups, which consists in heating the intermixed components to a temperature at which exother c reaction sets in, and in then llSlllg reaction to melt down the charge and complete the process.

l. The process of making an acid proof iron alloy consisting of heating a mixture of wrought iron, so t steel or the like with silicon until the chemical reaction between the Silicon and the sort iron is initiated, and of then using the heat of reaction for melting and finishing the alloy.

5. The process of making an acid proof iron alloy consisting of heating a mixture of soft iron which is low in carbon with silicon in form of ferro silicon until the chemical reaction between the silicon and the soft iron is initiated, and then using the heat of reaction for melting and finishing the alloy.

6. The process of making acid proof castings for chemical apparatus consistin of heating a charge of soft iron or steel mixed with ferro silicon in a flame heated furnace until the chemical reaction of the silicon upon the iron is initiated, and melting down the charge and finishing the alloy ready for pouring by the heat developed by the chemical reaction.

7. The process of making acid proof castings for chemical apparatus consisting of heating a charge of iron low in carbon mixed with ferro silicon in a reverberatory furnace until the chemical reaction of the silicon upon the soft iron is initiated, and melting down the charge and finishing the alloy ready for pouring by the heat developed by the chemical reaction between the iron and silicon.

8. The method of making acid proof castings for chemical apparatus consisting of heating a charge of soft iron low in carbon mixed with silicon in form of ferro silicon on a hearth in a furnace chamber to a temperature of between 1200 and 1300 centigrades for starting the chemical reaction between the iron and silicon and then melting down the charge and finishing the alloy ready for pouring by the heat spontaneously developed by said chemical reaction.

In testimony whereof I ailin my signature.

RICHARD WALTER. 

